An incentive to gift more subs would be to "throw in" additional gift subscriptions when purchasing bulk subscriptions.

For example:

5 gift subs gifts 5 subs for $24.95
10 gift subs gifts 12 subs for $49.90
20 gifts subs gifts 25 subs for $99.80
50 gift subs gifts 60 subs for $249.50

and so on. I'm thinking a 20% bonus at each tier, or the bonus could even tier up based on the amount. I believe it would create incentive to gift even more subs as the gifter would be given credit for the gifted amount, rather than the base amount.

In theory, you'll get more LARGER gift amounts, and that also increases the chance subs will be gifted to someone who will choose to continue said subscription as well.

I believe this would be a win for everyone.

Have a way to make a set of collections (not every collections playlist) subscription locked. There is a way to make a whole channel subscriber only viewing. Why not have it to where a broadcaster can lock a set of videos for those who chose to support the streamer financially while not taking away from those who can't or choose not to subscribe? In this concept, being able to keep past broadcasts and other uploaded content not in that collection completely open to everyone.
Idea behind it: I like to edit streams and other content into condensed highlights and upload them to Twitch and YouTube, my concept in doing this, is to remove the third step of redirecting subs to another place such as Patreon or Discord for access to videos early. Having a place on Twitch would be much easier to allow subscribers early previewing/first looks on content before it becomes public to everyone. This way it would give another perk to subscribing if this is something the broadcaster does, without forcing the viewer to be apart of another process.
But it's not just limited to the idea of early content viewing, this would also add another option of having permanent subscriber only content in the same way there is sub only streaming.

Provide custom servers for channel subscribers/twitch prime - this would allow streamers to play with their communities without the hassle of renting a server, plus you could charge more for prime if it was included to be able to join a custom server of the person you use your prime sub with. It would stop stream snipers as the streamer would have total control over the server, plus as it would be provided by Amazon, they would be able to use all the latest security to avoid it being DDOSS'd and hacked.

I feel this is really needed for certain games that are prone to being DDOSS'd on custom servers like Battlefield 4, and most likely a lot of other games.

Changing the way the founder badge works would be nice. The current system allows 10 founder badges for Affiliates and the Partners, 25.

My proposal is to allow people who sub in the first 24 to 72 hours of the streamer getting the sub badge to get a founder badge, if the streamer does not get up to at least 10 founders in that time frame, it will continue until the 10th founders badge is there. That way, for people with bigger communities, they people who sub day 1 still get rewarded, since they are still technically founders, just unlucky to be sub 26 by a few seconds.

It's just annoying when a community of people all sub day one, and majority get cut out due to small limitations. Also, most founders in many channels are no longer there, so it makes it even more scarce after years of streaming.

Even allowing the streaming an option/rules to the founders badge themselves as partners could be a good incentive.

There is already a setting to block gifted subs to channels i don't follow. We need to extend this setting to all channels. Some of us just don't like being gifted with subs for several reasons. I've been told that, if i want to support the streamer myself, i can gift a sub to another one. It's not the same, i don't care about others. I've been told i can upgrade my sub, but that will cost me double the price. I want to subscribe myself, period. I've come to the point where i cancel a gifted sub to a channel, just to sub myself after 1 minute, and that feels outrageous against the gifter, ruining our live experience.

If you have a high sub badge (as in you've been subbed to a particular streamer for a long time), but you liked the look of a previous sub badge better, it would be really nice to view earlier sub badges, especially if a streamer is offline who doesn't have a very active offline chat. I was thinking earlier that it might be nice to actually change your badge to an earlier one that you might think is prettier, but that might be too confusing and it would probably not be a good idea to deceive the streamer who probably doesn't always have time to actually hover over the badge and see how long the user has actually been subbed for LUL.

I think it would be a great idea for higher subscription tiers to be established for more money, with higher percentages of the amount of the subscription going to streamers as opposed to Twitch, kind of like how the current Twitch hierarchy works. For this idea, I was thinking of having something kind of similar to Patreon where you can subscribe and the higher tiered subscribers get access to more benefits. Maybe if you are subbed to a high enough tier on one streamer, you get a free Twitch Turbo or free Twitch prime? This could be beneficial for both Twitch and the streamers because the people who want their streamer more on a monthly basis can subscribe to a higher tier and even for a tier that may cost $100 USD, even if Twitch only claims 10%, that would still cover the price of Twitch Turbo and more! There are so many options for having more benefits for higher tiers, and maybe streamers can even choose which tiers they want to make available, and which ones they want to hide for their particular channel!